Funds are requested to acquire an automated tandem mass spectrometer optimized for peptide analysis. The instrument will be unique on our campus, and will provide high pressure liquid chromatography interfaced via nanospray/electrospray ionization, tandem mass spectrometry and MSn capability, product analysis with high resolution and high mass accuracy, software to support peptide and protein identification, the capability for isotope-free quantitation, high sensitivity and high throughput. It will be used by seven major researchers at the University of Maryland to characterize proteins associated with host/pathogen interactions, macrophage responses to diseases, and heme homeostasis; to support studies of protein structures and dynamics in solution; and to develop strategies for targeted alkylation of nucleic acids. The LTQ Orbitrap will be housed in the Mass Spectrometry Facility of the College of Chemical and Life Sciences. This commercially available, technologically sophisticated instrument will support meritorious projects on a shared use, highly cost-effective basis, and foster multidisciplinary interaction. [unreadable] [unreadable] [unreadable]